cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A159688 Triangle read by rows, denominators of Jakob Bernoulli's "Sums of Powers" triangle.

Original entry on oeis.org

1, 2, 2, 3, 2, 6, 4, 2, 4, 5, 2, 3, -30, 6, 2, 12, -12, 7, 2, 2, -6, 42, 8, 2, 12, -24, 12, 9, 2, 3, -15, 9, -30, 10, 2, 4, -10, 2, -20, 11, 2, 6, -1, 1, -2, 66, 12, 2, 12, -8, 6, -8, 12, 13, 2, 1, -6, 7, -10, 3, -2730, 14, 2, 12, -60, 28, -20, 12, -420, 15, 2, 6, -30, 18, -10, 6, -90, 6, 16, 2, 4, -24, 12, -16, 12, -24, 4
Offset: 0

Views

Author

Gary W. Adamson, Apr 19 2009

Keywords

Comments

Let the triangle = T. Row sums = 1. Row sums of n-th binomial transform of T = powers of (n-1). Then multiply the results by the partial sum operator, (1; 1,1; 1,1,1; ...) to obtain Bernoulli's "Sums of Powers".
Inserting zeros to account for (n+1) terms per row, right border = Bernoulli numbers: (A106458): (1, 1/2, 1/6, 0, -1/30, 0, 1/42, 0, -1/30, 0, 5/66, ...).

Examples

			Let row 0 = 1; followed by the corrected table, giving denominators:
   1;
   2, 2;
   3, 2,  6;
   4, 2,  4;
   5, 2,  3, -30;
   6, 2, 12, -12;
   7, 2,  2,  -6, 42;
   8, 2, 12, -24, 12;
   9, 2,  3, -15,  9, -30;
  10, 2,  4, -10,  2, -20;
  11, 2,  6,  -1,  1,  -2, 66;
  ...
The complete triangle with row 0 = 1, along with numerators:
  1;
  1/2,  1/2;
  1/3,  1/2, 1/6;
  1/4,  1/2, 1/4;
  1/5,  1/2, 1/3,  -1/30;
  1/6,  1/2, 5/12, -1/12;
  1/7,  1/2, 1/2,  -1/6,  1/42;
  1/8,  1/2, 7/12, -7/14, 1/12;
  1/9,  1/2, 2/3,  -7/15, 1/2, -3/20;
  1/10, 1/2, 3/4,  -7/10, 1/2, -3/20;
  1/11, 1/2, 5/6,  -1/1,  1/1, -1/2,  5/66;
  ...
		

References

  • Jakob Bernoulli, "Ars conjectandi", posthumously published in 1713, in which Bernoulli gives the table "Summae Potestatum (Sums of Powers) [cf. Young, p. 86].
  • Robert M. Young, "Excursions in Calculus", MAA, 1992.

Crossrefs

Cf. A106458.

Programs

  • Mathematica
    f[n_, x_] := f[n, x] = ((x+1)^(n+1) - 1)/(n+1) - Sum[Binomial[n+1, k]*f[k, x], {k, 0, n-1}]/(n+1); f[0, x_] := x; row[n_] := CoefficientList[f[n, x], x] // Reverse // (Sign[#]*Denominator[#])& // DeleteCases[#,0]&; Table[row[n], {n, 0, 15}] // Flatten (* Jean-François Alcover, Dec 29 2012 *)

Extensions

Extended to 15 rows by Jean-François Alcover, Dec 29 2012

A140814 a(0)=3, a(n)=A002445(n) for n >= 1.

Original entry on oeis.org

3, 6, 30, 42, 30, 66, 2730, 6, 510, 798, 330, 138, 2730, 6, 870, 14322, 510, 6, 1919190, 6, 13530, 1806, 690, 282, 46410, 66, 1590, 798, 870, 354, 56786730, 6, 510, 64722, 30, 4686, 140100870, 6, 30, 3318, 230010, 498, 3404310, 6, 61410, 272118, 1410, 6
Offset: 0

Views

Author

Paul Curtz, Jul 16 2008

Keywords

Crossrefs

Programs

  • Magma
    [3] cat [Denominator(Bernoulli(2*n)): n in [1..60]]; // Vincenzo Librandi, Nov 04 2018
  • Mathematica
    Join[{3}, Table[Denominator[BernoulliB[2 n]], {n, 60}]] (* Vincenzo Librandi, Nov 04 2018 *)

Formula

a(n) = A106458(2*n) + A106458(2*n+1).
a(n) = A027762(n) for n >= 1. - Georg Fischer, Nov 03 2018

Extensions

Edited and extended by R. J. Mathar, Jul 29 2008
Showing 1-2 of 2 results.